For most of her readers, the American author Diane Johnson is wholly identified with France and especially Paris. She's the author of novels like L'Affaire, Le Marriage, and Le Divorce — the last of which was made into a film.

So it comes as something of a surprise that Johnson's new book is about her roots in the American Midwest. And not only her own roots, but the roots of a family tree going back two centuries, painstakingly reconstructed from a trove of diaries and letters passed on by her mother.

Johnson tells NPR's Jacki Lyden that it was a minor snub from a French friend to get her interested in her own, American history.

"She said, you Americans know nothing about your history, and you're so indifferent to it, no wonder you keep invading the wrong countries. And I was kind of stung by that."

Interview Highlights

On a literary great great grandmother

Thank heavens there was a little bit of a literary impulse — Catharine Anne Martin sat down and wrote her memoirs in 1876, but she was born in 1800, and she's about — roughly a contemporary, a little bit younger than Jane Austen. And in 1826, when she went to Illinois, that's about the same time that the girls in Pride and Prejudice were much more comfortably outfitted, and living a very different life than pioneer grandmothers on the American frontier, which was what Illinois was at that time.

On her earliest recorded forebear

I didn't know that it would go back that far, and I didn't know about the first forebear that all of these people claimed as their ancestor ... Rene Cosset, a Frenchman, must have been a French soldier, who enters history in 1711, and he was captured by the British, because it was the time of the Queen Anne's War. And he, Rene, who is by now in America called "Ranna," because they can't pronounce Rene, Ranna Cossitt is mustered, traded to the French, and Ranna enters history because he didn't want to be repatriated. He said, no thanks, I'd rather be a prisoner my whole life and remain in America. No one quite knows why.